I do agree with the argument that computer science isn't really about computers: it's more general than that.
But I think there's similar weirdness about why math is so useful to (say) physicists. Why should the universe act this way?
"The miracle of the appropriateness of the language of mathematics
for the formulation of the laws of physics is a wonderful gift
which we neither understand nor deserve. We should be grateful for
it and hope that it will remain valid in future research and that
it will extend, for better or for worse, to our pleasure, even
though perhaps also to our bafflement, to wide branches of
learning."
http://www.dartmouth.edu/~matc/MathDrama/reading/Wigner.html
(I found Kolmogorov's claim pretty convincing though, that math is the distillation of much human experience, and so it shouldn't be too surprising that we find ideas from math pretty applicable. Maybe we perceive numbers and the structure of 3D visual space all over the place because of the way our brains are wired. But I'm not at all very knowledgeable about math or philosophy, so take this with a grain of salt.)
Tayssir
-- [Disclaimer: I only skimmed the Wigner link I offered. ;) Too much of what I perceived as gushing. Many of us see mathematics as a dull thing, imposed from above, and papers like those tend to trip my unreality meter.]